• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.44-50
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• 2019

HNIW is a high energy material and has four crystalline phases, it is known that the thermal properties of the material depend on the crystal phase. In this sturdy, the viscosity, mechanical and burning properties of a solid propellant with nitrate ester polyester(NEPE) system with respect to the crystal phases of HNIW. According to the crystal phase of HNIW, the mechanical properties of the cured propellant did not change considerably, however differences were observed in the burning properties. Considering both a high density and stable burning properties, the optimum crystal phase of HNIW can be identified as the main factor influencing to the NEPE system propellant.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.153-158
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• 2019

The overall environmental regulations of the industry have been strengthened due to environmental pollution that occurred in modern society. Therefore, R&D of selective reduction catalyst (SCR) is needed to meet these environmental regulations. This paper carried out thermal analysis to develop the pneumatic damper valve (PDV), which is a key component of SCR system. For thermal analysis, verification of material properties was performed first. Verification was performed through the thermal properties test and the thermal tensile test of the specimen, and the results were reinforced with the material properties to enhance the reliability of the thermal analysis.The heat analysis was intended to identify thermal characteristics with PDV in total of three materials (SM400B, SS275, SB410) applied under the conditions of use of PDV, and to confirm the structural stability of the PDV.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.490-494
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• 2011

Nanocomposites of blends of polyethyleneterephthalate (PET) and polyamide66 (Nylon66) containing natural and organically modified montmorillonite clays (PM, $Cloisite^{(R)}$ 25A and 15A) were prepared by melt mixing. DSC results showed that the addition of clay changed the crystallization behavior of PET/Nylon66 nanocomposites. Clay C25A was observed to most significantly change the crystallization temperature than other clays in blends of PET and Nylon66, which may be caused by the difference in interaction with matrix polymers. AFM results also showed that the lowest value of surface roughness was observed for nanocomposites containing C25A indicating the smooth and relatively homogenous surface. Mechanical properties measurement showed the similar results. Contact angle was measured to study the difference in hydrophobicity. An increase in contact angle was observed for nanocomposites with C25A or C15A due to the increased hydrophobicity.

• Polymer(Korea)
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• v.36 no.3
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• pp.275-280
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• 2012

Poly(amic acid)s were successfully synthesized from 1,4-bis(4-aminophenoxy)benzene (1,4-APB) or 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) with pyromellitic dianhydride (PMDA), 3,3'-4,4'-benzopenonetetracarboxylic dianhydride (BPDA) and $p$-phenylenediamine ($p$-PDA) and then they were effectively converted into polyimide films by thermal imidization. The chemical structure and thermo-mechanical properties of polyimide films were examined using Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analyzer (TGA), thermo-mechanical analyzer, dynamic mechanical analyzer (DMA) and universal tensile machine (UTM). The moisture absorption, thermal and mechanical properties of polyimide films decreased with increasing the amount of 1,4-APB and HFBAPP. The polyimide films using HFBAPP showed lower properties than that of 1,4-APB at the same ratio, but it displayed better thermal properties and lower moisture absorption at the similar coefficient of thermal expansion (CTE) with a copper. On the basis of our finding, it is concluded that 4-component polyimide films could be utilized for base films for flexible copper clad laminates (FCCL) of flexible printed circuit boards.

• Composites Research
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• v.30 no.4
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• pp.235-240
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• 2017

Animal glue, a water-soluble adhesive, has been used historically for high-performance traditional furniture despite the disadvantage of weakness against moisture. Many scientists studied the ways to improve water resistance of animal glue. Improvements on the interfacial, thermal, and water resistance properties of wood sandwich composites (WSC) was studied with carbon nanotube (CNT) wt% in animal glue. Real-time temperature of WSC was measured after WSC was heated with increasing CNT wt%. Lap shear test was performed to determine the interfacial properties of wood and animal glue with CNTs. Water resistance properties of animal glue were determined by lap shear test using specimens dipped in water and the results were compared with the dry case. Hydrophobicity of animal glue by static contact angle was correlated with the variation of lap shear test. Interfacial, thermal, and water resistance properties for animal glue were improved with properly added CNTs.

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.345-353
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• 1998

Metal organic chemical vapor deposition (MOCVD) of copper using three Cu( I ) precursors. (hfac)Cu (VTMS) (hfac= hexafluoroacetylacetonate, VTMS= vinyltrimethylsilane), (hfac)Cu(VTMOS) (VTMOS= vinyltri¬methoxysilane) and (hfac)Cu(A TMS) (A TMS= allyltrimethylsilane) was studied. The thermal stability and the gase¬ous phase reaction mechanism of Cu( I ) precursors were identified using $^1H$-, $^I3C$-NMR and Fourier transform infra¬red spectroscopy. It was found out that thermal stability of liquid phase (hfac)Cu(VTMS) and (hfac)Cu(VTMOS) were better than that of (hfac)Cu(A TMS) using FT - NMR. From in-situ FT - IR experiments, the disproportion reaction of Cu(hfac). the decomposition reaction of Cu(hfac), and cracking of free hfac ligand were observed. Also the effect of gaseous phase reaction on the deposition rates and film properties was investigated. The minimum temperature that deposition of copper films from (hfac)Cu(A TMS) was as low as 60$^{\circ}$C and such a low deposition temperature compared with those of other Cu( I ) precursors is believed to be related with weaken Cu- A TMS bond.

• Journal of Korea Foundry Society
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• v.43 no.3
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• pp.107-136
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• 2023

Natural silica sand was commonly used for sand casting of cast steel products, and chromites sand was used to suppress seizure defects due to the lack of thermal properties of silica sand. However there are disadvantages such as deterioration by repeated use, system sand mixing problem, difficulty separating and removing, increased during mold according to high density and to being waste containing chrome. Recently, industrial waste reduction and atmospheric environment improvement have been highlighted as important tasks in the casting industry. In order to solve the problems that occur when using foundry Sand and to improve the environment of casting factories, various artificial sands that can be applied instead of natural silica sand have been developed and introduced. Artificial sands can be classified into artificial sand manufactured by the electric arc atomization or gas flame atomization, artificial sand manufactured by the spray drying & sintering process, artificial sand manufactured by the sintering & crushing process and exhibit different physical properties depending on the type of raw-minerals and manufacturing method. In this study, comparative evaluation tests were conducted on the physical properties of various foundry sands, mold strength, physical durability, thermal durability, and casting test pieces. When comprehensively considering the actual amount of molding sand used according to density, the mold strength according to the shape of sand, the physical and thermal durability of foundry sand, and the heat resistance characteristics of foundry sand, 'Molten artificial sand A1' or 'Molten artificial sand B' is judged to be the most suitable spherical artificial sand for casting of heavy steel castings.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.223.1-223.1
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• 2010

CFRP는 우수한 기계적 강도와 경량 특성으로 인하여 NGV/FCV용 가스를 저장하기 위한 재료로서 널리 이용되고 있다. 탄소 섬유와 에폭시로 이루어진 CFRP는 화염 노출 시 매트릭스의 열적 분해 반응에 의해 급격한 물성 변화를 일으킨다. CFRP 메트릭스가 100kW/$m^2$ 이하의 열플럭스에 노출되는 경우 표면온도 변화에 따른 용기 내부로의 열확산 메카니즘을 규명하기 위해서는 시간에 따른 경계조건의 변화를 명확히 할 필요가 있다. 본 연구에서는 Fuel bed type 가열장치의 열플럭스를 계산하였으며 계산된 열플럭스에 노출되는 CFRP 용기 표면의 온도 변화 측정 실험을 수행하였다. 또한 측정 결과를 보고된 문헌의 결과와 비교하였다.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.277-280
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• 2002

유,무기 입자가 첨가된 고분자 복합 소재는 고분자 매트릭스에 기계적, 열적 특성을 향상시킬 뿐만 아니라 이들의 다양한 기능성을 부여할 수 있다[1]. 특히 첨가되는 유,무기 입자가 나노 크기로 감소할 경우 단위무게 당 표면적이 증가하므로 이들의 효과가 더욱 현저히 나타나는 장점이 있으며 그 밖에 고유한 광학적, 전기적 특성을 나타내게 된다[2-4]. 그러나 나노 입자간의 강한 표면 작용력으로 인해 균일한 분산상을 얻기 힘든 단점[5]이 있어 최근 이를 개선하기 위한 연구가 활발히 진행되고 있다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.49-52
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• 2002

합성 고분자의 생분해는 환경 보존이라는 측면에서 중요시 되고 있으며 봉합사나 bone fixation, 그리고 implant와 같은 의학적 응용면에서도 상당한 관심의 대상이 되어오고 있다 glycolic acid, L-lactic acid, $\varepsilon$-caprolactone에 근거하는 지방족 폴리에스터는 생분해성 봉합사로서 응용되고 있으나 여전히 열적, 기계적 가공특성과 같은 적정특성들이 부족하다.$^1$ 한편 폴리아마이드는 유사한 구조를 갖는 폴리에스터와 비교할 때에 상대적으로 높은 유리전이온도와 높은 융점을 가지고 있는 반면 높은 흡습성으로 인한 물성저하가 야기될 수 있다. (중략)